Typically, an elevator car travels along a pair of opposing guide rails located in a shaft or hoistway. It is customary to employ four roller guides per elevator car to guide the elevator car along the guide rails as the car is moved in a shaft or hoist way. Two of the rollers guides are secured to the upper portion of the elevator car in such a manner as to engage the corresponding guide rails. The remaining two roller guides are secured to the lower portion of the elevator car in a similar manner to engage the corresponding guide rails.
Over time, guide rails are subjected to various forces that can deform one of more portions of the guide rail or buckle joints that hold sections of the guide rail together. This results in misalignment of one or more sections or portions of the guide rail. Such destructive forces include high winds which can cause some high-rise buildings to sway as much as eighteen inches off center for a total swing of three feet. Over time, this wind load and the resulting sway of the building may cause rails to misalign due to the constant flexing of the guide rail. Misalignment of portions or sections of the guide rails can also result from settling of the building. Further, elevator cars can become out of balance when the elevator car is structurally modified to improve its aesthetic appearance or for other commonly known reasons. Misalignment of various sections or portions of the guide rails and/or an out of balance elevator car can drastically affect the ride quality of the elevator car as it travels in a shaft or hoistway.
Various roller guide designs have been proposed in an attempt to address some or all of these adverse conditions. However, the prior designs have various inherent disadvantages and/or are unable to adequately compensate for all adverse conditions an elevator car and/or the guide rails may experience over prolonged use.